Polyolefins such as high density polyethylene (HDPE) homopolymer and linear low density polyethylene (LLDPE) copolymer can be produced using various combinations of catalyst systems and polymerization processes. In some end-use applications, it can be beneficial for the catalyst system employed to produce low molecular weight and high melt flow polymers without the use of hydrogen. Accordingly, it is to these ends that the present invention is generally directed.